The objective of the Tissue Specificity Core is to provide initial data on the tissue specificity of putative gamete-specific antigens by assessing the expression of the antigen and of the mRNA for the antigen in a variety of tissues. The Core will also serve as a source of different primate tissues for use in the sub-projects. 1. The presence of mRNA for putative gamete-specific antigens in non- gonadal organs will be sought using Northern analysis. The core will also utilize RT-PCR studies (reverse transcriptase polymerase chain reaction) for more sensitive detection of low abundance mRNAs for selected antigens of special interest. 2. Potential cross-reactivity of antibodies to various gamete antigens in non-gonadal primate tissues will be examined by immunohistochemistry and by competitive ELISA assays. 3. The Core will serve as a source of large numbers of different primate tissues. Tissue samples and isolated RNA will continue to be made available to investigators for use in tissue specificity and related studies carried out in the investigators' laboratories. The data generated from the Tissue Specificity Core will be a first step in assessing the gonadal specificity of gene products which are candidates for contraceptive vaccines. In addition, analysis of cross-reactivity of sera from fertility trials will aid in assessing the performance of the immunogens. The studies performed by this core form the basis for further immunopathologic studies to be carried out as needed in the individual projects to further investigate tissue cross-reactivity.